1. Field of the Invention
The present invention generally relates to power-saving circuits, more particularly, relates to a power-saving circuit with improved way of switching for saving electrical power.
2. Description of Related Art
Electrical energy is used to power electronic devices, e.g. computers, Personal Digital Assistants, etc. Such electronic devices may be equipped with power-saving functions not only to save power but also for extending the life of the electronic devices. As such, power-saving circuits are usually integrated with the electronic devices.
Referring to in FIG. 4, a conventional power-saving circuit 900 is used for saving electrical energy by detecting human activities in a localized area. The power-saving circuit 900 includes a passive infrared sensor 92, a processing circuit 93, a driving circuit 94, and a relay 95 that are serially coupled in that order. The processing circuit 93 includes a converting circuit 931 and an amplifying circuit 932 electrically connected to the converting circuit 931. The relay 95 is connected to a lamp 96. A power supply 91 is used for providing electrical power to the processing circuit 93, the driving circuit 94, and the lamp 96.
The passive infrared sensor 92 receives infrared rays emitted from an object such as a person in the localized area, and outputs a current signal to the processing circuit 93. The current signal is converted to a voltage signal by the converting circuit 931. The voltage signal outputted from the converting circuit 931 is amplified by the amplifying circuit 932. The driving circuit 94 receives the amplified voltage signal, and outputs a control signal indicating a presence of that person in the localized area. The relay 95 is switched on by receiving the control signal. Thereby, the lamp 96 is provided with electrical power. When that person leaves the localized area, the infrared sensor doesn't receive the infrared rays, therefore no voltage signal is supplied to the driving circuit 94. The relay 95 is switched off. As such, there is no electrical power supplied to the lamp 96.
However, the relay used in the power saving circuit 900 is a mechanical type switch, which may not contact well after working a period of time, such that the power-saving circuit wouldn't achieve a power saving object.
Therefore, a power-saving circuit with an improved way of switching for saving electrical power is needed in the industry to address the aforementioned deficiencies and inadequacies.